Collapsible tap



Jan. 14, 1936. F. NELL CQLLABSIBLE TAP Filed Feb. 7, 1.954 l INVENTok. 'ederic Nell BYv ATTORNEY..

2 Sheets-Sheet 2 .nu QM INVENTOIL HedercNe ATTORNEY.

. vided with grooves I4 which grooves are engaged Patented Jan. `14, 1936` PATENT OFFICE COLLAPSIBLE TAP Frederic Nell, Waynesboro, Pa., assignor to Landis Machine Company, Waynesboro, Pa., a corporation of Pennsylvania.

Application February `7, 1934, Serial No. 710,171

1.1 Claims.

This invention relates to collapsible taps such as are used for cutting screw threads in holes, in pipe,.tubes, etc. and its object is to provide a collapsible tap having improved means for co1- lapsingthe thread cutting elements and improved means for restoring the thread cutting elements to Voperative or thread cutting position.

A further object is to provide an improved co1.- lapsible tap of the character disclosed having a removable head.

A still further object is to provide improved means'for locking the tap in thread cutting position and improved meansfor unlocking, the locking means.

Further .objects and advantages will become apparent as the description proceeds. l

Referring to the accompanying drawings which are made a part hereof and on which similar reference characters indicate similar parts,

Figure 1 is a sectionV on line I-I of Figure 3 showing the thread cutting elements in expanded.

enlarged scale of means for positioningthe thread"` cutting elements .in operating or thread `cutting position, l. Figure 5, a section on line 5--5 of Figure 3 showing: one of the collapsingY springs, and

lFigure 6, a section on line S-Bof Figure 3 showing the expanding or set-uprspring.` 1

In.. the `drawings reference character Ifindicatesa stock'or body portion to which heads II` of various vsizesmay be attached asby means of screws. I5. The head II carries threadcutting elements I2 radiallyslidabIe in .slots therein.

The inner edges of the cutters I2 engage surfaces` I5 on a plunger head I3. The cutters I2 are proby tongues IS on the plunger head. `A solid key I'I on the head II engages a slot in the forward end of the body portion I0'. `The plungerhead I3 is secured by means of an adjusting pin 20 to` the plunger I8.. The pin serves to adjust the head I3 relative to the plunger I8. 'The axial position ofthe head I3 determines the radial position of the thread cutting elements. `It will be apparent' that when` thehead is in its outermost 'u cutting elements are drawn inward radially Ato;`

(Cl. lll- 145) move them out of engagement with the work wherebythe tap may be freely withdrawn from the work. The adjustable pin 20 has an enlarged end which engages a socket in the forward end of the plunger I8. A locking element 2| has a serrated forward end which engages the serrated end of the adjustable pin 20. A spring 22 surrounding the locking element urges it into engagement with the enlarged end of the adjusting pin 20. The locking element 2| is prevented from turning by a pin 40. The adjusting pin 20 preferably has a polygonal socket 4I in which a corresponding wrench may be seated for rotating the adjusting pin to adjust the head I3 axially. Due to the serrations on the end of the pin 20 and the cooperating locking pin 2 I, thepin 20 is `held in locked axial position so that jarring vibrations cannot change" the radial position of the thread cutting elements I2. 'I'he plunger I 8-is lockedin forward position by means of a latch 23 shown inFigure l.V This latch is pivotally mounted on a pin 24 on the body portionV I0. The plunger I8 is cut out to receive a suitably hardened plate 25 against which an arm of the latch 23 engages to holdthe plunger in forward position. The plunger is held in its forward position by engage` ment. of a surface 31 on the latch 23 with the surface 38 on the plate 25. A latch controlling ring or collar 26 is mounted on the bodyV member I0. This collar has ears or lugs 2l in which are secured holding rods 29 vby means of bolts orscrews 28. The rods 29 are secured at their forward ends in a ring 30 which ring is engaged by the work for moving the collar 26 rearwardly of the VAbody portion. The-rods 29 and ring 30 may be clamped to the collar 26 in various positions depending upon` the length of the thread desired, oneextreme adjustment of the ring 30- being indicated in dottedlines in Fig. l. A latch rack 3I is se' cured in the collar 26 by screws 39. This rack has teeth engageable with teeth on the latch 23. Springs32 shown in Figure 6 and springs 34 shown in'Figure 5 are positioned in tubular.` sections of the collar 26 and operate to collapse and expand the cutters. The springs 32 have one'end seated in the bottom of a tubular section of the collar 25 and have their other end positioned against a pad 33 whichengages the front side of a'plate35. The plate is secured by means of a bolt `Sli to the plunger I8. The springs 34 are Vfitted 'also within the ring 26.A One end of the springsengages paid 33` which rests against the forward edge of the plate 35 and the othervend engages pad 53 which rests against a post 42 which is inserted in the` body member I0. A lever 45 is pivoted at 45 position to. collapse the cutters, said first-mentioned spring being arranged to supplement the reaction of said second spring on said plunger.

7. A collapsible tap comprising a body member, a plunger axially `slidable inthe body member, radially movable thread cutting elements mounted in the body member and having their inner edges in engagement with beveled portions Y of the plunger, a latch pivotally mounted on the axis of the body member and having one element adapted to engage a portion of the plunger to lock it in forward or thread cutting position, a collar "surrounding the body member having a rack ment, a plunger engaging said chasers to move` the same to operative position, latching means for said plunger including an axially movable member and a spring between said member and said plunger, said latching means further comprising a transverse pivot pin disposed in an axial recess in the plunger and a latchmember pivoted on said pin and provided with an offset latching portion engaging the plunger adjacent the central axis thereof and means including said axially movable member for operating said latchmeans mounting said chasers for radial movement, a plunger engaging said chasers to move the same into operative position, a latch-controlling collar surrounding said plunger provided with a toothed portion and axially movable with respect to the plunger, a latch for the plunger pivoted adjacent the longitudinal axis of said plungerand having a portion engaged by the toothed portion of said collar, a spring `between said collar and said plunger and means including said spring for moving the plunger to collapse the chasers to inoperative position upon release of said latch by said collar.

10. A threading device comprising a body member, chasers mounted therein for radial movement, a plunger engaging said chasers to move the same to operative position, a latch-controlling collar surrounding said plunger and axially movable with respect to the plunger, a latch for said plunger a-nd controlled by said collar, a plurality of longitudinal springs disposed in recesses in said collar and arranged tor control the movement of said collar and of said plunger when the latter is released by the operation of said latch andY another spring disposed in a recess in said collar engaging the body member and plungerV 

